Substituted adenines -and preparation
thereof



United States Patent 3,215,696 S-SUBSTITUTED ADENINES AND PREPARATION THEREOF Ren Arthur Henri Denayer, Uccle, Belgium, assignor to UCB (Union Chimique-Chemische Bedrijven), S.A., a corporation of Belgium No Drawing. Filed Oct. 2, 1962, Ser. No. 227,724 Claims priority, application Belgium, Oct. 13, 1961, 485,487, Patent 609,114; May 18, 1962, 496,207, Patent 617,814; Aug. 31, 1962, 496,985, Patent 621,979

13 Claims. (Cl. 260252) The present invention relates to a new method for preparing 3-substituted adenines of the formula wherein Ris a substituent selected from the group consisting of straight chain alkyl, alkenyl and alkinyl radicals, branched chain alkyl, alkenyl and alkinyl radicals, hydroxya-lkyl, dialkylaminoalkyl, cycloalkyl, heterocyclic, benzhydryl and substituted benzhydryl radicals and a radical (CH ),,X wherein X represents a member selected from the group consisting of aromatic and heterocyclic residues and substituted derivatives thereof and n a .positive integer of from 1 to 4.

According to the invention, these derivatives are prepared using 4,6-diamino--formy1amino-pyrimidine as a starting material.

-In preparingthe 3-substituted adenine derivatives, two alternatives are to be considered:

(a) When R represents an alkyl, alkenyl, alkinyl, dialkylaminoalkyl, cycloalkyl, 'heterocyclic, benzhydryl or substituted benzhydryl or the radical -(CH X wherein n and X have the same meaning as above, 4,6-diamino-5- formylamino-pyrimidine is reacted with the corresponding R halogenide. The reaction product is a quaternary ammonium salt of 3-R-5-formylamino-4-,6-diaminopyrimidine. After setting free the base by means of an alkali, the product is allowed to cyclize in alkaline medium at a temperature below 100 C. to form the corresponding adenine:

Rvhaving the same meaning as above and Hal representing a halogen atom.

(b) When R represents a hydroxyalkyl radical, 4,6- diarnino-S-formylamino-pyrimidine is reacted with the appropriate alkylene oxide. Here also quaterniz'ation of the pyrimidine occurs, followed by a cyclization as under 3,215,690 Patented Nov. 2, 1965 ice (11). Starting from ethylene oxide and water, the reaction is as follows:

Hon

| CIIr-CHzOH The 4,6-diamino-S-formylamino-pyrimidine used as starting material is easily prepared according to the method of L. F.Cavalieri et al. (J. Am. Chem. Soc. 71 (1949), 553'36) from 4,5,6-triamino-pyrimidine, the latter in its turn being prepared according to the method of R. K. Robins et al. (J. Am. Chem. Soc. 75 (1953), 263).

The invention relates also to the following derivatives of adenine as new products: B-ethyl-adenine, '3-n-nony1- adenine, 3-propargyl-adenine, 3- (2-hydroxyethyl)-adenine, 3-(2,3-dihydroxy-propyl)-adenine, 3-(2-dimethylaminoethyl)-adenine, 3-(2-diethylaminoethyl)-adenine, 3-benzyl-adenine, 3-furfuryl-adenine, as well as their pharmaceutically acceptable addition salts with organic and inorganic acids.

A convenient'way has been found to difiFerentiate the 3-substituted adenine derivatives from the corresponding 7-substituted adenine derivatives.

From the studies of the UV. absorption spectra (in 0.1 N HCl solution or in 0.01 N NaOH solution) it results that the 3-substituted adenine derivatives possess an isobestic point at xz285i2 ma, whereas 7-substituted compounds have an isosbestic point at A:250:8 11111..

Comparative values are given in the following table.

Isosbestic Compounds: point (m 3-rnethyl-adenine 283.5 7-methyl-adenine 250 3-ethyl-adenine 286 3-n-nonyl-adenine 285 3(3',3-dimethylallyl)-adenine .285 .5 7-(3',3'-dimethylallyl)-adenine 250 3-propargyl-adenine 286 3- (Z-hydroxyethyl) -adenine 285 3-(2,3-dihydroxypropyl)-adenine 286 3-(2-dimethylaminoethyl)-adenine 287 7-(2-dimethylaminoethyl)-adenine 25 0 3-(2-diethylaminoethyl)-adenine 283 7- (Z-diethylaminoethyl -adenine 25 0 7-(3-dimethylaminopropyl)-adenine 248 7-cyclopentyl-adenine 25 0 3-benzyl-adenine 286 7-benzyl-adenine 250 7-[2-(N-morpholino)-ethyl]-adenine 254 Isosbestic Compounds Continued point (m 7-[2-(4-phenyl-1-piperazino) -ethyl]-adenine 25 8 3-furfuryl-adenine 286.5 7-furfuryl-adenine 7- (p-chlorobenzylhydryl -adenine 25 2 It has been discovered that the compounds according to the Formula I mentioned hereinabove have useful pharmacological activities, i.e., analeptic, bronchodilator, vasoand coronarodi lator, tranquilizing and even diuretic activities.

The following examples are given by way of illustration only and not by way of limitation Example J.Preparatin of 3-methyl-adenine 1.53 g. of 4,6-diamino--formylamino-pyrimidine are dissolved hot in 125 ml. of dimethylformamide. 1.56 g. of methyl oxide is added thereto and the mixture is refluxed between 80 and 120 C. for one hour.

The solution is evaporated under vacuum and the mass is taken in up in water. Potassium carbonate is added until precipitation of the 3-methyl-adenine occurs. The precipitate is filtered off and dissolved in water. After treatment of the solution with activated charcoal the solution is allowed to crystallize out.

0.45 g. of 3-methyl-adenine monohydrate is obtained; melting point: 300-302 C. (after sublimation). Yield: 27%.

The corresponding sulfate, prepared according to the conventional method, has a melting point of 268-270 C.

evaporated in vacuo, is filtered off. with acetone.

(b) 3-n-n0nyl-adenine.The quaternary salt formed under (a) is dissolved with the appropriate quantity of a 5 percent by weight solution of sodium hydroxide. The obtained solution is heated at 5060 C. for 5 minutes and then salted out by adding solid potassium carbonate.. The oil which separates out is crystallized from acetone-water Then it is washed (1/ 1). The product crystallizes with 0.5 molecule of Water. Melting point: 224-225 C. Yield: 38%.

Analysis for C H N J/2H O: Percent N Calculated 25.9

Found 25.9

Analysis for C H N OBr: Percent N Calculated .m 26.5

Found 26.5

To this bromide a 5 percent aqueous solution of potassium hydroxide is added and the mixture is heated at 60 C. At first a solubilization is observed, followed by crystallization.

Analysis for 6 7 5- Percent N The crystalline mass is filtered oil and recrystallized Calculated 41-90 from water. 1 g. of 3-(3',3'dimethylallyl)adenine is ob- Found 42-03 tained. Melting point: 229-230 c.

The U.V. spectrum analysis of the monohydrate gives Analysis for CmHmNs: Percent N the following results: Calculated 3446 l Found 34.25 s1 t xM'. Vi. M. .0

oven in M m E ax 2.3%0 The U.V. spectrum analysis gives the following data:

01 0.1 N 274 236 15, 900 1. 26 9 E2011 0.01 N 272 242 13,600 1. 46 solvent 9 A 6 2 These values are in perfect agreement with those cited H0101 N 274 238 17,500 1. 32 for 3-methyl-adenine by P. Brookes and P. D. Lawlcy NaOH O'OIN 273 245 13300 (J. Chem. Soc. London, 1960, p. 539-45).

Example 2.Preparati0n of 3-ethyl-adenine (a) Quaternary salt of 4,6-diamino-5-formylamin0-3- ethyl-pyrimidine.-l9 g. of ethyl iodide are added to a suspension of 15.3 g. of 4,6-diamino-5-formylaminopyrimidine in 300 ml. of dimethyl-formamide.

After heating for 5 hours at 60 C. a quaternary salt is formed. This salt, after vacuum evaporation of the dimethyl-formamide, is filtered otf and then washed with acetone and with alcohol.

Analysis for C7H9N5: Percent N Calculated 42.9 Found 43 4 Example 3. Preparati0n of 3-n-n0nyl-adenine (a) Quaternary salt of 4,6-diamin0-5-f0rmylamin0-3- n-nonyl-pyrimidina-IO ml. of n-nonyl bromide are added to a suspension of 7.5 g. of 4,6-diarnino-5-formylamino-pyrimidine in 200 ml. of dimethylformamide.

After heating for 3 hours at 120-140 C. a quaternary salt is formed which, after dimethylformamide has been Example 5 .Preparation of 3-pr0pargyl-adenine (a) Quaternary salt of 4,6-a'iaminl0-5-formylamin0-3- pr0pargyl-pyrimidine.15 g. of 4,6-diamino-5-formylamino-pyrimidine are suspended in 200 ml. of dimethylformamide. 12 ml. of propargyl bromide is added thereto. The mixture is heated slowly up to 110 C. and this temperature is maintained for 3 hours. The solvent is evaporated in vacuo. The quaternary salt, which appears in the form of a resin, is taken up in isopropanol. Formation of crystals is observed. 24 g. thereof are collected, a quantity corresponding to a yield of 89% (b) 3-propargyl-adenine.The crystals of the quaternary salt formed under (a) are dissolved in water and the obtained solution alkalized with a 20 percent aqueous solution of potassium hydroxide. 3-propargyl-adenine crystallizes out at once. The latter can be recrystallized from water while avoiding heating the solution to boiling Example 6.Prepanati 0n of 3-(2-hydr0xyethyl)adenine (a) Quaternary salt of 4,6-diamino-5-formylamina-3- (Z-hydroxyethyl)-pyrimidine.A stream of ethylene oxide is passed through a5 percent aqueous solution of 4,6-diamino-5-formylamino-pyrimidine heated to about C. An increase of the pH value to 11l2 is ob served, which indicates quaternization.

Analysis for C H N O; Percent N Calculated 39.1 Found 39.1

Example 7.Preparation of 3-(2,3-dihydr0xypr0pyl)- adenine (a) Quaternary salt of 4,6-diamin-5-f0rmylamin03- (2,3-dihydr0xypropyl)-adenine. The procedure is the same as in Example 6(a), except ethylene oxide is replaced by the equivalent quantity of epoxypropanol.

(b) 3-(2,3-dihydroxypropy l) adenine.Applying the same operating condition as in Example 6(b), the corresponding 3-(2,3-dihydroxypropyl)-adenine is obtained in the form of crystals. Melting point: 298-,-300 C. Yield: 40%.

Analysis for C H N O Percent N Calculated 33.4 Found 33.4

Example 8.-Preparation of 3-(2-dimethylamin0ethyl)- adenine FIRST METHOD (a) Quaternary salt of 4,6 diamino 5 fo rmylamino- 3 (2 dimethylaminoethyl) pyrimidine.l5 g. of 4,6- diamino 5 formylamino pyrimidine are suspended in 1 liter of dimethylformamide. 10.75 g. of Z-dimethylaminochloroethane are added thereto and heating is performed for 5 hours at 80 C.

The solvent is evaporated in vacuo, then the residue is taken up in a 20 percent aqueous solution of hydrochloric acid. The latter is filtered on activated charcoal and the solvent is evaporated under vacuum, leaving a pasty residue.

By treating this residue with ammonia until alkalinity (pH 8) and filtering, 9.5 g. of the starting pyrimidine is recovered.

(b) 3 (2 dimethylaminoethyl) adenine.--To the filtrate obtained under (a) after precipitation with ammonia solid potassium hydroxide is added so as to obtain a KOH concentration of 5%, then the mass is heated for 5 minutes at 65 C. The solution is salted out with solid potassium carbonate. The solid which separates is filtered off and taken up in enough hot water to dissolve it completely. After cooling, 5.5 g. of 3 (2 dimethylaminoethyl)-adenine are separated by filtration.

The latter is chromatographically purified on an alumina column, using ethanol as eluent. The purified product melts at 2ll-212 C. Yield: 25%.

Analysis for C H N Percent N Calculated 40.75 Found 40.85

SECOND METHOD (a) Quaternary salt 0 4,6 diam'ino 5 fo rmylamino- 3 (2 dimethylaminoethyl) pyrimidine-16 g. of 4,6- diamino 5 formylamino pyrimidine are suspended in 250 ml. of water. Then 8.2 g. of sodium acetate and 14.4 g. of 2 dimethylaminochloroethane hydrochloride are added thereto. This reaction mixture is thereafter heated for 15 hours at 80 C., then for 6 hours at 80- 100 C.

The solution is then half-concentrated under vacuum and ammonia (d.=0.93) is added thereto until alkalization. After cooling, filtration is carried out to separate 9.4 g. of the starting pyrimidine.

(b) 3 (2 dimethylaminoethyl) adenine.To the filtrate obtained. under (a) after precipitation with ammonia, solid potassium hydroxide is added so as to obtain a KOH concentration of 5%; then the mass is heated for 10 minutes at 65 C. The solution is salted out with solid potassium carbonate and in this manner an oil separates out.

The latter is chromatographed on an alumina. column, using ethanol as an eluent.

In this way 3 (2 dimcthylaminoethyl) adenine melting at 211-212 C. is obtained. Yield: 16%.

Example 9.Preparation 0f 3- (Z-diethylaminoethyl) adenine The first method of Example 8 is followed using the corresponding quantity of 2 diethylaminochloroethane (13.45 g.), instead of 2 dimethylaminochloroethane. After purification by chromatography, 3 (diethylaminoethyl) adenine melting at 209-210 C. is obtained. Yield: 28%.

When the second method of Example 8 is followed but 2 diethylaminochloroethane hydrochloride (17.1 g.) is used, two products are isolated chromatographically, i.e. 9 (2 diethylaminoethyl) adenine (melting point: 18l182 C.) and 3 (2 diethylaminoethyl) adenine (melting point: 209-210" C.). Yield: 20%.

Analysis for C11H18N6:

3-substituted Q-substituted der1vative derivative Percent N Percent N Calculated 35. 87 35. 87 Found 36.0 36.05

Example 10.Preparali0n 0f 3-benzyl-adenine 278-279 C. is obtained. Yield: 42%. 5

Analysis for C H N /2H O: Percent N Calculated 29.9 Found 29.6

The U.V. spectrum analysis for the semi-hydrate gives the following results:

Solvent 7\ Max. A Min. e Max. e 280 E 260 H01 0.1 N 275 23s 17, 700 1. 43 NaOH 0.01 N 274 246 12,700 1. 42

Example 11.Preparati0n of 3-furfuryl-adenine Operating as in Example 1, 4.6 g. of 4,6 diamino 5- formylarnino-pyridine are heated for 4 hours with 3.5 g. of furfuryl chloride.

2.1 g. of B-furfuryl-adenine monohydrate melting at 244245 C. is obtained. Yield: 30%.

Analysis for C H N -O-H O: Percent N Calculated 30.03 Found 29.95

The U.V. spectrum analysis for the monohydrate gives the following data:

1. A method for preparing 3-substituted adenines having the formula:

ing the liberated free base with a cyclizing agent in alkaline medium at a temperature below 100 C., and (4) separating the 3-substituted adenine formed from the reaction medium.

2. .A method for preparing 3-substituted adenines havl ing the formula:

in which R is hydroxyalkyl, comprising (1) heating tos gether 4,6-diamino-5-formylamino-pyrimidine with alkylene oxide, (2) treating the resulting quaternary salt of 3-R-5-formylamino-4,6-diaminopyrimidine, wherein R has the.meaning as previously defined, with alkali, (3) treating the liberated free base with a .cyclizing agent in alkaline medium at a temperature below C., and (4) separating the 3-substituted adenine'formed from the reaction medium.

3. A 3-substituted adenine having the formula:

wherein R is a member selected from the group consisting of alkyl' of from 2 to- 9 carbon atoms, lower alkenyl,

lower alkinyl, lower hydroxyalkyl, lower-dialkylaminoalkyl, cyclopentyl, furfuryl, benzhydryl, chlorobenzhydryl,

perazino, (CH -lower alkylpiperaz-ino and (CH phenylpiperazino, and n is a positive integer of from 1 to 4. 4. A therapeutically acceptable acid addition salt of a 3-substituted adenine as'claimed in claim 3.

5. 3-ethyl-adenine.

6. 3-n-nonyl-adenine.

7. 3-propargy1-adenine.

8. 3-(2-hydroxyethyl)-adenine.

9. 3-(2,3-dihydroxypropyl)-adenine.

10. 3-(2-dimethylaminoethyl)-adenine.

11. 3-(Z-diethylaminoethyl)-adenine.

12. 3-benzyl-adenine.

13. 3-furfuryl-adenine.

References Cited by the Examiner Baker et al.: Jour. Org. Chem, vol. 19, pages 632-7 (1954).

Denayer et al.: Comptes Rendus, tome 253, pages 2994- i 2996 (December 1961).

Leonard et al.: Jour. Am. Chem. Soc., vol. 82, pages 620-3 (1960).

Montgomery et al.: Jour. Am. Chem. Soc., vol. 83, pages 630-635 (February 1961).

' NICHOLAS S. RIZZO, Primary Examiner. 

1. A METHOD FOR PREPARING 3-SUBSTITUTED ADENINES HAVING THE FORMULA:
 2. A METHOD FOR PREPARING 3-SUBSTITUTED ADENINES HAVING THE FORMULA: 